The present invention relates to a method for obtaining wrapper sheets which are particularly adapted for forming the outer wrapper in cigarette packs of the so-called "soft or american" type.
In the manufacture of the so-called "soft or american" packs, a group of cigarettes, usually twenty in three superposed rows of seven, six and seven, is firstly wrapped inside a tinfoil wrapper, and the said tinfoil-wrapped pack is then finally enclosed inside an outer wrapper consisting of a substantially rectangular paper sheet wrapped around the tinfoil pack so that one of its smaller edges overlaps the other smaller edge and is caused to adhere thereto by glueing along a line parallel to and close to one of the longitudinal corners of the cigarette pack. The outer paper wrapper terminates, in correspondence of the top head end of the pack (i.e. the end which is intended to be opened for use) at a short distance from the head end corners, and it is usually closed by a closure label (such as for example a duty stamp) which bridges over the said top head end and is glued by its extremities to the edges of the outer paper wrapper on both major sides of the cigarette pack. At the bottom head end of the cigarette pack, the outer paper wrapper is mechanically folded so as to form two superposed flaps which are glued together.
By using rectangular wrapper sheets, the above mentioned wrapping operation gives origin to an inconvenience which affects the outer appearance of the cigarette pack. In fact, the mechanical folding of the outer wrapper sheet in correspondence of the bottom head end of the pack leads to the formation of two flaps one of which has the contour of an isosceles trapezium, while the other has the contour of a rectangular trapezium, due to the actual impossibility of folding the angle section of the edge of the sheet which is superposed and glued to the other underlying edge.
In order to avoid this inconvenience, and to obtain a cigarette pack in which the bottom end of the outer wrapper sheet results from the superposition of two identical flaps having each the contour of an isosceles trapezium, presently there are employed outer wrapper sheets which are rectangular and present one bevel angle. The use of the said bevelled rectangular sheets does not create any problem whenever they are fed to the wrapping machine from a feeding hopper containing a pile of superposed sheets. If on the other hand it is desired to cut the single sheets from a continuously running paper web, it is necessary to provide for pick-up means (usually pneumatic means) for picking and eliminating the waste off-cuts consisting of small paper triangles resulting from the cutting of the bevel angle. The said pick-up means obviously constitute a constructive complication for the wrapping machine.
According to the present invention, the wrapper sheet for forming the outer wrapper in cigarette packs of the so-called "soft or american" type, is characterized by the fact that it has the outline of a rectangle with a bevel angle and, in correspondence of the angle adjacent to the said bevel angle, with an appendix projecting out of the ideal contour of the rectangle, said appendix being exactly alike to the triangle cut out from the bevel angle. The said wrapper sheet is obtained from a continuous paper web by subjecting the running paper web to subsequent cutting operations, each cutting operation providing an angular cut comprising a longer section transverse to the running direction of the web, and a shorter terminal section, forming with the said longer transverse section an angle equal to the bevel angle. It is apparent that each cutting operation takes place without the production of any waste off-cuts.
When the outer wrapper sheet is folded around the tinfoil pack, the flaps which close the bottom end of the pack result to be both shaped as isosceles trapeziums, while the appendix comes to be concealed under one of the said flaps, and therefore it does not disturb the outer appearance of the cigarette pack.
The above and other features of the invention, and the advantages deriving therefrom, will appear evident from the following detailed description of one preferred embodiment, made with reference to the Figures of the attached drawings.